180,000 children have been forced to flee their homes with little means of protection, shelter or assistance, UNICEF said Friday.
In a statement, the agency said it had received "horrific reports" from southern Syria, including the death of an entire family in the city of Daraa.
According to UNICEF, efforts to reach a peaceful solution to the ongoing fighting there appear to have failed.
"Humanitarian assistance and protection are neither a privilege nor a luxury; they are a fundamental right of every Syrian boy and girl," Geert Cappelaere, UNICEF's regional director for the MENA region, said in the statement.
He went on to urge the international community to step up its efforts to provide humanitarian assistance to those suffering most from the crisis.
"If we collectively fail in this duty, children will continue paying the heaviest price of a war not of their making," he said.
Syria has only just begun to emerge from a devastating conflict that began in 2011, when the Assad regime cracked down on demonstrators with unexpected ferocity.
